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Tiny combined bluetooth\amps to mess with (following Tomz lead)

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  • Tiny combined bluetooth\amps to mess with (following Tomz lead)

    People out there may be aware that a few of us seem to be messing around making tiny bluetooth builds, one of the issues one comes across is putting all the components into the minature cases (included Visaton BF37 for scale). Over the past 6 months i've been purchasing random boards from all corners of the globe to see what will fit best into my can builds, where space is at a premium. I came across these two boards, which seem to be pretty good for their size and can use low power sources.

    The larger of the two on paper is capable of getting 2x50 watts per channel (if you beleive the write up) @ 24v or 15watts @ 12v. I've used it at 5v, being the lowest available and it operates pretty good off the singular 18650 battery. I'm currently looking at a downward firing design, with the ability to turn the top to turn the power on and adjust the volume using the pot.

    The smaller board is a 2x5w (@6.5v) combo board, which has a customisable CSR8645 bluetooth module. Which @ 5v will put out 3w per channel. Unknown to me was the size of this board and i still dont know how the guys on youtube managed to solder to the custom pins as it is very very small and close together. I'm afraid using a lower gauge of wire will affect sound or performance, so i soldered headers onto to and bent the pins to allow me to use 18 gauge. I think although others have used the step up boards before, that they may cause a bit of an issue as i have have some teething problems. I did get it working quite well off one 18650 battery yesterday and instead of calling it a success, decided to shorten the power leads, put the 2200v capacitor and use the step up\boost module, which at 90% volume triggered some form of protection where it put the volume down to 10% but leaves the phone as where it was. Nothing can increase the volume either, even adjusting the tactile volume buttons dont do anything. I've managed to do this on two of the three modules and removing the boost module appears to be causing the sound to become a bit horrible at any volume, which i cant quite get my head around as the only thing that had changed was the removal of the circuit and shortening of the leads. One thing i have thought of doing is from the boost converter soldering on a DC DC isolating converter to send a clean 5v to the module. Not sure with the limited information provided if anyone has any past experiences with similar issues on different or the same boards that i could try?

    please ignore the fact that some of the leads are missing off the bluetooth board, i started unsoldering lines to check their connection and had to then entertain the kids, so never got back to it.

    The experiences have been quite interesting as i'm very new to this form of electronics, but enjoying the steep learing curve, even if i want to break something when things go back in a fit of rage.


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  • #2
    I think they are about 30mm x 30mm in size, which is about half a size bigger than those micro PAM amps that pump of 2x3watts, but with the added bonus of having bluetooth on board.
    Attached Files

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    • Jake
      Jake commented
      Editing a comment
      I've used several of these boards. They sound clean, and pair without issue. Haven't had one go bad yet. Good for low power.

  • #3
    Who wants a tiny BT boombox? I want to do something like the old JVC PC-V77, with detachable satellite speakers and a subwoofer built into the central box :-).

    ...and I might have started on something that might just morph into that. A build that's basically been about 15 years in the making (sigh)....

    Click image for larger version

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    Brian Steele
    www.diysubwoofers.org

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    • #4
      Originally posted by Brian Steele View Post
      Who wants a tiny BT boombox? I want to do something like the old JVC PC-V77, with detachable satellite speakers and a subwoofer built into the central box :-).

      ...and I might have started on something that might just morph into that. A build that's basically been about 15 years in the making (sigh)....

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      Honestly I do want to get an old ghetto blaster but.....haven't found the right one for the right price to fix up.

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      • #5
        Jake maybe there is something loose or happening in my build, when it worked it was very clear and the quality was what I wanted. I just need.to figure it out as I really want this one to.work.

        Have you used the csr programming module?

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        • Jake
          Jake commented
          Editing a comment
          No, I haven't used the programming one. What happened to this board? Did you fry it? Looks possible based on your soldering, no offense. For tiny 3w boards like this, I use cat6 wire. It fits in the holes, and is decent quality. Also a fine soldering tips goes a long way.

        • 3rutu5
          3rutu5 commented
          Editing a comment
          Jake Not sure to be honest, the headers I soldered on looked alright, how I got 2mm wire onto the headers are a bit questionable but they don't touch. The two boards operate ok until I put the voltage booster on and then it goes really quite after going loud. I'm going to get some CAT5 cable, didn't even think of using that

      • #6
        3rutu5, also try the PE Consolidated 22g solid core wire. Works great for power and ground. Heres a test rig i have set up.

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        • #7
          Originally posted by Jake View Post
          3rutu5, also try the PE Consolidated 22g solid core wire. Works great for power and ground. Heres a test rig i have set up.
          Great tip with the CAT cable, grabbed me a few meters as well as one of those soldering station helpers with the magnifying glass. I honestly didnt think about using a Lan cable at all, but when you think about it, some things can get power over LAN....I had a look at the connections for the power on my first board and they were actually pretty good, so for a test i wound back the booster to just 5V incase the board itself struggles to take 6.5v as advertised and it worked well. One downside to the Visaton BF37's is their low sensivity only pushing out around 748db, so up at its loudest with 5v's it isnt super loud, but sounds pretty good. I tested a 2" aliexpress driver and it went up quite a bit louder, so i have worked out the next amp for the other project i'm working on......

          Problem is i have 3 small builds, all a bit different to each other, but very similar

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          • #8
            Wow, that's a nice little board. My dream would be to work with one of those custom circuit board companies to make a board that combines 2x5W, volume pot, BT4.X, and an 18650 charge/boost controller all in one. Maybe even a .1 channel output. Unfortunately it's been a while since EE201 so it's likely to remain a dream.

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            • #9
              Originally posted by jdhill View Post
              Wow, that's a nice little board. My dream would be to work with one of those custom circuit board companies to make a board that combines 2x5W, volume pot, BT4.X, and an 18650 charge/boost controller all in one. Maybe even a .1 channel output. Unfortunately it's been a while since EE201 so it's likely to remain a dream.
              i'm sure i read somewhere there is almost an all in one board available, just a bit expensive.

              I have my 3d printer doing the body of my latest design which will house the above....just hope i dont run out of filament .

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